Xeon E 2456 's Advantages
Higher base frequency (3.3GHz vs 2.4GHz)
Lower TDP (80W vs 250W)
Xeon 6740E 's Advantages
Released 6 months late
Higher specification of memory (6400 vs 4800)
Larger L3 cache size (96MB vs 18MB)
More modern manufacturing process (5nm vs 10nm)